As an auxiliary heating means for heating a living space or the like, an electric blanket, an electric pad and the like are mainly used. However, in the case of electric devices such as an electric blanket and an electric pad, electromagnetic waves are generated together with an electric field from a heating wire through which an electric current flows. Continuous exposure to such electromagnetic waves is harmful to a human body.
In order to reduce the direct or indirect damage due to the electromagnetic waves generated in an electric blanket or an electric pad, there has been devised a fluid circulation type heating device in which a heated high-temperature fluid is circulated through a pipe surrounded by a heat dissipation member such as a blanket or pad.
For example, Korean Patent Publications Nos. 1038576, 0312643 and 1033668 disclose a fluid circulation type heating device of the type in which a fluid heated by a channel heater is circulated by using a circulation pump, and a fluid circulation type heating device of the type in which a fluid is circulated by a pressure generated due to vaporization of a fluid.
In such a fluid circulation type heating device, when a fluid, for example, water is heated, a part of the water becomes a vapor, thereby increasing and the internal pressure of a water circulation path. If the fluid circulation path is sealed, a pump, a check valve, etc. may be damaged due to an increase in the internal pressure, or the weakest part of the fluid circulation path may be damaged. Therefore, it is necessary to discharge the vapor to the outside. In the conventional fluid circulation type heating device, a part of a storage tank for storing a fluid is opened in order to prevent an increase in pressure. However, in such a case, if the device falls, the water in a water tank may be spilled out. In extreme cases, a user may be burned by spilled hot water. In addition, when foreign substances such as dust or the like are introduced into the water tank through the opened part, the pump, the check valve and the like may be damaged by the foreign substances.